Influence of pressures up to 50bar on two-stage anaerobic digestion.

•The influence of pressure on anaerobic digestion up to 50bar was examined experimentally.•Increasing pressure decreases pH value in the methane reactor until 6.53.•Increasing pressure increases methane content over 90%.•Increasing pressure decreases specific methane yield until 0.26Lg–1 CODadded.•The pressurized methane reactor operates very stable.